In transferring the film into a video signal, the film (running at 24 frames/second), is usually transferred in "real time" to video (30 frames/second - 60 fields/second), for treatment (for example, automated electronic colouring, special electronic effects, electronic rotoscoping, electronic post productions). Thus each frame of film transferred is not transferred to one frame (two fields) of video. In fact, the transfer is what is known as "3:2 pull down" where the frames of film are deposited on three fields of video and the next frame of film onto two fields of video, the next frame of film into three fields of video and so on. The order may be reversed--two fields, then three fields, then two fields and so on. The result when played back is interfield motion within the same frame of video.
To retain and maintain frame integrity it has been proposed to transfer the film at a sped up rate of 30 frames per second to video. Each film frame now occupies one video frame thus simplifying treatment. Thereafter, it has been proposed that the rate of video playback be converted to twenty-four frames per second. This is purported to be accomplished using the "slo-mo" (slow motion) mode of the video machine, to convert its thirty frames per second recording of the film to an equivalent twenty-four frames per second speed. See the article entitled "Black and White in Colour" in The BKSTS Journal, Nov., 1983.
Other proposals have been made. In this regard, see:
U.S. Pat. No. 4,402,018 which purports to teach a process for converting images on a motion picture film into a video signal, said film being recorded in the form of twenty-four frames per second and said video signal being displayed at sixty fields per second, said process comprising: (A) repeating video signals derived from a (B) repeating video signals derived from each of the next three film frames two times in order to provide the next six video fields; whereby said four film frames produce a 4-2-2-2 conversion into video signals; (C) generating reference gating signals for identifying the beginnings and ends of each 4-2-2-2 conversion; (D) arranging each 4-2-2-2 conversion responsive to said reference signal to have a specific position relative to a vertical blanking period in said video signals; and (E) recording four fields on each turn of a spiral track on a recording disk which is rotating at 900 R.P.N;
U.S. Pat. No. 4,337,484 which purports to teach an apparatus in which the video disk frames are reread while a shutter blocks the film in order to have during the rereading operation, the time necessary for advancing the kinescope film without causing violent mechanical stresses. In order to pass from the television standard with thirty frames per second to the cinematographic standard of twenty-four frames per second, one frame out of five is not recorded on the film and the film advanced without any rereading;
European Application Pat. No. 152,141 purports to teach a record carrier having a spiral-shaped or concentric ring-shaped information track on which a programme is recorded in a sequence of two fields in every turn of the track. It requires (n) film frames per unit time to be reproduced in order to realize reproductions with the original frame speed. The nominal playback speed of the carrier is (m) video pictures of two fields per unit time, where (m) is greater than (n). The read apparatus can move the scanning point forwards or backwards in a radial direction over a distance corresponding to the radial displacement over one revolution using a jump-signal generator (13), switch (14) and motor (17);
For each film frame only two consecutive fields are recorded. During read-out the scanning point is moved backwards and/or forwards to preceding and following turns of the track. Each time consecutive film frames are reproduced the number of film frames reproduced per unit time is (n) and the number of video pictures reproduced is (M). This allows reproduction of film recorded at twenty-four frames per second (n=24) in accordance with U.S. TV standard. No need to repeat picture information at expense of playing time.
European Application Pat. No. 152,141 which also purports to teach that for each film frame recorded only two consecutive fields are recorded and during read-out the scanning point is moved backwards and/or forwards to a preceding and a following turn of a track, respectively in conformity with a predetermined pattern, which turn is situated at a distance corresponding to at least the radial displacement over one revolution in such a way that each time consecutive film frames are reproduced as consecutive sets of at least two fields corresponding to the same film frame, the number of film frames reproduced per unit of time being the specific number n and the number of video pictures reproduced being m.
In particular in the above situation of a film comprising twenty-four frames per second and a television standard of thirty pictures per second, the invention may be characterized further in that n=24 and m=30 and said pattern is such that for every cycle of four film frames two sets of two fields belonging to a different film frame and two sets of three fields belonging to a different film frame are reproduced by reproducing two of the eight recorded fields belonging to said four film frames twice every cycle in conformity with said pattern.
In another embodiment this system is characterized further in that in said cycle of four film frames, corresponding to ten reproduced fields, a backward jump over two fields is effected after every fourth and every sixth field and a forward jump over two fields is effected after every fifth field;
U.S. Pat. No. 3,366,733 purports to teach a system for recording video signals derived from a motion picture film on a disk. The motion picture advance is controlled in synchronism with the rotation of the disk whereby, for example, succeeding film pictures are recorded alternating as two and three fields for twenty-four frames per second type film, or three film pictures are recorded in four fields, one film picture in three fields, in alternating sequence for a sixteen frames per second type film. General rules are developed for the various cases. The recording of sequential fields is controlled in synchronism with the rotation of the disk and the alternating recording patterns are counted out; and
Canadian Letters Pat. No. 953,815 which purports to teach a method of converting television video signals representing colour information to colour motion picture film. The video information occurring at sixty fields per second is recorded as a three colour black and white separation master at seventy-two frames per second. Each group of three colours on the black and white separation master is printed as one colour film frame to produce the twenty-four frames per second colour film. Each of the three colours on each colour film frame comes from the same point in time in that it comes from the same TV field and problems of colour fringing are thereby eliminated. In addition, problems of motion irregularity are purported to be eliminated in that the conversion from the sixty field per second television signals to the twenty-four frames per second colour film does not involve the double use of particular ones of the colour groups on the black and white separation master. The conversion is purported to occur because seventy-two separation colour successive frames are recorded on the black and white separation master during the time of sixty colour television fields, and there is no motion irregularity since there is no double use of information.
See also U.S. Pat. No. 4,157,570 and European Application Pat. No. 152,141.
U.S. Pat. No. 4,157,570 purports to teach a TV-cine conversion projector adapted to carry out the ordinary film projection of the projector at the feeding rate of the film frames of substantially twenty-four frames/second and eighteen frames/second, while, in co-operation with a TV camera tube such as a vidicon, it can convert the projected images of the film at the feeding rate of the film frames of substantially twenty-four frames/second and 18 frames/second into TV pictures scanned at the scanning rate of sixty fields/second or fifty fields/second, and comprises a main shaft driven at a constant speed.
The proposals discussed above suffer from a number of difficiencies. Some reduce the information content during the transfer process from one medium to the other. Some of the systems introduce interfield motion making the processing of the video tape difficult. For example, in colouring of film so transferred, colour spills over from one part of a picture (for example, a hand) to another (for example, a pocket) due to interfield motion.
Still further, and referring to the non-real time playback referred to in the article "Black and White in Colour" in The BKSTS Journal, Nov. 1983, the proposal is deficient. Use of the "Slo'Mo" (slow motion) mode of the video tape recorder causes line interpolation to fill in missing information and causes vertical registration inaccuracies and abnormalities. Furthermore, the horizontal resolution is dramatically reduced.
It is therefore an object of this invention to provide an improved process of transferring film to video or film which has been previously transferred to video for the treatment thereof and after treatment converting to a real time play rate, thereby providing a superior product to those preceding Applicant's invention.
Further and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of an embodiment thereof.